zdrada69 wrote:Do you have any experiance with new motorized points ? Are they unreliable ?

I have tried out the manual and one-way ones, and they look functionally the same as the new electric ones. The problems are trains derailing and poor electrical pickup on that huge dead frog, and I simply find them not reliable enough to support any sort of automated operation. The mechanism to switch the point is something else entirely, with lots of options for that - those new ones, servos, Cobalts, etc. Points are one of the reasons my plans for a new layout are on hold at the moment.

I had a long chat with Paul Blake while enjoying his model of Orbost at a local show a couple of weeks ago, and we were both lamenting the point problem and what we could do with some good ones!

And as Doug implies, reliable points are very nearly a make-or-break issue for a layout based on the Tamar bridges. A poor second choice would be to make one line a dummy (maintenance work in progress!) and run trains only in one direction. That old exhibition tradeoff between reliability (especially for a one-man show) and realism.

I'm going to make ......or get made for me....a custom shallow angle point for the location at the West end of the bridge. The twin track will then disappear off the layout and run round behind the layout....and merge back on the East side of the bridge as a single line.

Behind the scenes there will be a half-traverser sort of point made from a piece of flexitrack fixed onto a pivoted piece of wood or similar....hopefully motorised, as will the viewable set of points. This way, I can have two trains running in opposite directions....

One of the things that has held up my decision to proceed with this project was the one big "challenge" I was likely to set myself......getting moving traffic on the Tamar Bridge.

Over the past few weeks I've been doing a bit of sketching out of designs for what I was hoping to be a successful traffic movement system that would not look out of place in the relatively shallow profile of the road deck. And I think I've proven to myself that is actually is possible to achieve. My objective was to have two separate mechanical link conveyors...one for the slow lanes and one for the fast lanes.....running under the road deck surface, with a run-around system at each end of the bridge "off layout" so that vehicles move across the bridge and disappear through a hole in the layout backboard....and the a few seconds later reappear running in the opposite direction. And I intend the fast lane to run at a slightly higher speed to the slow lane!!!

So far, I've created a prototype chain link and low profile track in which it runs. Each chain link is approx 0.9mm long and is 3D printed in one piece...and once I get the final design, I'll need a couple of hundred or so to form the two chains. I've also designed and printed a short section of an early design for the road deck.....complete with four built-in tracks. I've sourced and obtained some PTFE strip that will act as the road surface. This strip is a nice light grey colour that will be perfect!! And finally, I've purchased a bag of small magnets ....tiny little buggers as well!!..... for burying in both the chain links and the underside of the vehicles.

Well! Its early days....but I seem to have made quite a good start on what are some of the technical bits for the layout. I'm not intending to post many images of progress on the tricky bits until I get a bit further on with the design and build...but I am taking photos as I go, so will reveal all eventually!

Doug .....that's fascinating to see another special layout beginning to come together I really like way you have altered the view for the layout .... an area I knew well , one thing I find in responses to your posts is how many of us are having to work around the horrible points problem of t gauge , so many needing to find a way to have a working layout without the dreaded points being involved myself included ......always hopeful an alternative arrives eventually for us all ......look forwards to seeing how your work of art evolves in time ......

Its been a few days since my last post......but I've been beavering away on the design and construction of parts for the Tamar Bridge.

I'm concentrating on the automation mechanism for the lanes of traffic at present. I have purchased a couple of drive motors that have built in reduction gearboxes and have fitted a 3D printed pinion to one of them. On the basis that I'll not be able to break the bridge down into pieces for transport, I'm looking at an assembly that will be almost five feet long!!!.....just within the maximum size I can get ins the back of my car!!!

I've been making some slow but steady progress with 3D printing parts for the road bridge....but things are not yet at the point where I want to post progress shots. Perhaps in a couple of weeks time!

I've got a few parts for the drive system printed....including two of the biggest parts I've printed so far..both overnight printing jobs!

Today, I obtained a copy of a book all about the Royal Albert bridge....which has a number of really useful detailed photos that will help designing the component parts. I'd been chatting with a fellow volunteer at the Tramway Museum and she mentioned she also helps out in the bookshop at Ecclesbourne Valley Railway and they had just got in a as-new copy of a book on the bridge....so I had to buy it!!

Here's a set of 3d printed parts for the assembly at one end of the Tamar Bridge to handle the four lanes of road traffic:

P1020032_red.JPG (84.96 KiB) Viewed 2892 times

Top to bottom, left to right.....back row, a two-part chassis (which was too big to print in one piece), supports for the road surface round the run-around wheels; middle row, the end section of the bridge deck with the ramps that feed the traffic onto the run-around wheels, which are next in the picture. Finally the bottom row, the two motors with attached reduction gearboxes and 3d printed pinions, two dirt cheap speed controllers (which I may have a go at seeing how they run trains!!) and the motor mounting clamps.

I need to get some 3mm diameter rod and some nuts and bolts....and see how they all fit together! Kind of sad really....but its "Seniors' Day" every Wednesday at B&Q, so I'll try getting what I want then...and get my old git's discount!